As device densities continually increase on a semiconductor wafer, the trend is to incorporate multiple circuits into a single monolithic integrated circuit. For example, current computer systems run four or eight processors, and those plurality of processors are fabricated on a single monolithic integrated circuit. In the future, a computer system will likely run an even larger number of processors in a multiprocessor system. Incorporation of a larger number of processors into a single monolithic integrated circuit increases the volume on a semiconductor wafer occupied by the plurality of processors.
Referring to FIG. 1A, an integrated circuit such as a multiprocessor system is fabricated on an area 102 of a semiconductor wafer 104. Referring to FIG. 1B, a cross sectional view of the semiconductor wafer 104 along line A--A of FIG. 1A shows the area 102 having the integrated circuit fabricated on a first face 106 of the semiconductor wafer 104. In the prior art, integrated circuits are fabricated on only one side of a semiconductor wafer.
In the prior art where integrated circuits are fabricated on only one side of a semiconductor wafer, as larger numbers of integrated circuits for an electronic system are incorporated into a single monolithic integrated circuit, the volume on a semiconductor wafer occupied by the plurality of integrated circuits for the electronic system increases. Thus, fewer dies of electronic systems fit onto a semiconductor wafer with larger numbers of integrated circuits. The rate of manufacture of the number of dies fabricated per semiconductor wafer decreases.
However, more integrated circuits may need to be incorporated into a die as electronic systems advance in technology. Thus, a means for compactly fabricating a plurality of integrated circuits of an electronic system on a semiconductor wafer is desired.